Elucidation of the radius and ulna fracture mechanisms in toy poodle dogs using finite element analysis

Fractures occurring in the distal radius and ulna of toy breed dogs pose distinctive challenges for veterinary practitioners, requiring specialized treatment approaches primarily based on anatomical features. Finite Element Analysis (FEA) was applied to conduct numerical experiments to determine stress distribution across the bone. This methodology offers an alternative substitute for directly investigating these phenomena in living dog experiments, which could present ethical obstacles. A three-dimensional bone model of the metacarpal, carpal, radius, ulna, and humerus was reconstructed from Computed Tomography (CT) images of the toy poodle and dachshund forelimb. The model was designed to simulate the jumping and landing conditions from a vertical distance of 40 cm to the ground within a limited timeframe. The investigation revealed considerable variations in stress distribution patterns between the radius and ulna of toy poodles and dachshunds, indicating notably elevated stress levels in toy poodles compared to dachshunds. In static and dynamic stress analysis, toy poodles exhibit peak stress levels at the distal radius and ulna. The Von Mises stresses for toy poodles reach 90.07 MPa (static) and 1,090.75 MPa (dynamic) at the radius and 1,677.97 MPa (static) and 1,047.98 MPa (dynamic) at the ulna. Conversely, dachshunds demonstrate lower stress levels for 5.39 MPa (static) and 231.79 MPa (dynamic) at the radius and 390.56 MPa (static) and 513.28 MPa (dynamic) at the ulna. The findings offer valuable insights for modified treatment approaches in managing fractures in toy breed dogs, optimizing care and outcomes.

Finite element study on post-screw removal stress in toy poodle radius with different plate designs and screw arrangements

Background

The study employs finite element analysis to investigate stress distribution in the radius of toy poodles after screw removal. The examination focuses on the biomechanical implications of varied screw hole configurations using 1.5 and 2.0-mm locking compression plates (LCPs) with notched head T-Plates.

Aim

To provide a noninvasive approach to analyzing the immediate consequences of screw removal from the radius bone in toy poodles. Specifically, it explores the impact of varied plate designs and screw arrangements on stress distribution within the forelimb bones.

Methods

The study constructs a three-dimensional bone model of the toy poodle's forelimb based on computed tomography (CT) images. Simulations were designed to replicate jumping and landing from a 40 cm height, comparing stress distribution in the radius post-screw removal.

Results

The analysis reveals significant variations in stress distribution patterns between the two LCPs. The radius implanted with the 2.0-mm LCP displays a uniform stress distribution, contrasting with the 1.5-mm plates. Localized stress concentration is observed around the screw holes, while trabecular bone regions near the screw holes exhibit lower stress levels.

Conclusion

The study highlights the plate designs and screw configurations that affect bone stress in toy poodle forelimbs post-screw removal. The findings provide valuable insights for veterinarians, aiding informed decisions in veterinary orthopedic practices.

Relationship between clinical parameters and malformations in dogs diagnosed with atlanto-axial instability

Atlanto-axial instability is a common disease that affects toy-breed dogs. Most cases of atlanto-axial instability are congenital. Furthermore, patients with atlanto-axial instability are predisposed to other concurrent diseases. Therefore, this study aimed to retrospectively determine the presence of concurrent diseases in cases with atlanto-axial instability using imaging data and analyze the relationship between clinical parameters and the incidence of complex malformations. The clinical data and imaging findings of 41 toy-breed dogs diagnosed with atlanto-axial instability were analyzed using their medical records and imaging data. Occipital dysplasia (17/27), atlanto-occipital overlapping (22/34), dens dysplasia (27/41), Chiari-like malformation (8/34), syringomyelia (5/34), lateral ventricular enlargement (20/36), and intracranial arachnoid cyst (5/35) were observed in patients with atlanto-axial instability. The body weight of the patients in the groups with atlanto-occipital overlapping and lateral ventricular enlargement was lower than that of those in the groups without these diseases (1.78 ± 0.71 vs 2.71 ± 1.15 kg, P = 0.0269, 1.60 ± 0.40 vs 2.75 ± 1.08 kg, P = 0.001, respectively). Furthermore, when the correlation between the total number of concurrent diseases and the age at onset and body weight was examined, it became clear that lower body weight was associated with the incidence of a greater number of concurrent diseases. Thus, the findings of this study suggest that toy-breed dogs are more likely to present with complex malformations and should be evaluated carefully with additional examinations and treatment methods.

Intraoperative hypertensive crisis in a dog with functional paraganglioma of the gall bladder

A 15-year-old spayed female mongrel presented with anorexia and an abdominal mass. The mass originated from the gall bladder and was surgically resected along with divisionectomy of the central hepatic division. Paroxysmal hypertension and tachycardia were noted during manipulation of the mass. Following resection, arterial blood pressure decreased significantly. Histopathological analysis confirmed a diagnosis of neuroendocrine neoplasm. Immunohistochemical staining for synaptophysin and chromogranin A yielded diffuse and strong positive results, while gastrin was positive in only 10% of the cells. The preoperative elevated concentrations of catecholamine in the urinalysis showed a marked decrease after surgery. Based on these findings, the tumour was diagnosed as a functional paraganglioma of the gall bladder. The patient has undergone regular thoracic radiographs and ultrasound examinations and, until 431 days after surgery, has shown no signs of metastases or recurrences. Based on our literature search, we report the first case of functional paraganglioma of the gall bladder in a dog.

Quantitative evaluation of the biomechanical and viscoelastic properties of the dog patellar tendon in response to neuromuscular blockade at different stifle angles

The patellar tendon (PT) is crucial for maintaining stability and facilitating movement in the stifle joint. Elastography has been recognized as a prominent method for evaluating PT properties in humans and dogs. The utilization of oscillation methods in canine studies remains limited despite their extensive documentation in human studies. Our study represents the first effort to quantitatively assess and compare the effects of muscle relaxant on the biomechanical and viscoelastic characteristics of the PT at varying stifle angles in living dogs. Five healthy female beagles were used in this study. Biomechanical (tone, stiffness, and decrement) and viscoelastic (relaxation time and creep) properties of the PT were measured using MyotonPRO (Myoton Ltd, Estonia) prior to and following administration of rocuronium (0.5 mg/kg/body weight) at normal, extended, and flexed positions. Rocuronium was selected for its safety, controllability, and widespread clinical use in veterinary anesthesia. Two-way analysis of variance showed that tone, stiffness, and decrement were significantly higher (P < 0.001) in the control group than in the muscle relaxation group. At the same time, relaxation time and creep were significantly lower (P < 0.001) in the control group than in the muscle relaxation group. The findings indicate that stifle angle position and muscle rexalant administration fundamentally alter the biomechanical loading conditions of the PT, leading to changes in its viscoelastic properties. Therefore, this novel quantitative data could benefit clinical settings that necessitate accurate and objective methods for risk identification and monitoring PT biomechanics in dogs.

Proof-of-concept study of the caninized anti-canine programmed death 1 antibody in dogs with advanced non-oral malignant melanoma solid tumors

BACKGROUND

The anti-programmed death 1 (PD-1) antibody has led to durable clinical responses in a wide variety of human tumors. We have previously developed the caninized anti-canine PD-1 antibody (ca-4F12-E6) and evaluated its therapeutic properties in dogs with advance-staged oral malignant melanoma (OMM), however, their therapeutic effects on other types of canine tumors remain unclear.

OBJECTIVE

The present clinical study was carried out to evaluate the safety profile and clinical efficacy of ca-4F12-E6 in dogs with advanced solid tumors except for OMM.

METHODS

Thirty-eight dogs with non-OMM solid tumors were enrolled prospectively and treated with ca-4F12-E6 at 3 mg/kg every 2 weeks of each 10-week treatment cycle. Adverse events (AEs) and treatment efficacy were graded based on the criteria established by the Veterinary Cooperative Oncology Group.

RESULTS

One dog was withdrawn, and thirty-seven dogs were evaluated for the safety and efficacy of ca-4F12-E6. Treatment-related AEs of any grade occurred in 13 out of 37 cases (35.1%). Two dogs with sterile nodular panniculitis and one with myasthenia gravis and hypothyroidism were suspected of immune-related AEs. In 30 out of 37 dogs that had target tumor lesions, the overall response and clinical benefit rates were 6.9% and 27.6%, respectively. The median progression-free survival and overall survival time were 70 days and 215 days, respectively.

CONCLUSIONS

The present study demonstrated that ca-4F12-E6 was well-tolerated in non-OMM dogs, with a small number of cases showing objective responses. This provides evidence supporting large-scale clinical trials of anti-PD-1 antibody therapy in dogs.

Osteosarcoma of the hyoid bone in a cat

Case summary

A 10-year-old male neutered Abyssinian cat was presented with the chief complaint of a right pharyngeal mass. On palpation, the mass was easily palpable; it appeared well demarcated and mobile, and oval in shape. Radiographic examination showed a radiopaque pharyngeal mass, which was revealed to be a well-demarcated mass lesion with a radiopaque marginal area on CT examination. The inside of the mass was uniformly well enhanced on contrast CT examination. A three-dimensional image reconstructed from the CT images strongly suggested that the mass originated from the right stylohyoid bone. No abnormal lesions were observed in the thoracic and abdominal CT examinations. Surgical excision of the mass was scheduled 3 weeks after the first admission. The mass was bluntly separated from the surrounding musculature and resected together with the ipsilateral epihyoid bone adjacent to the mass. Histopathological examination of the resected mass showed neoplastic cells with osteoid formation, and the mass was histopathologically diagnosed as an osteosarcoma. The postoperative recovery from anaesthesia was uneventful, and the cat began feeding on its own from the third postoperative day. The 3-month postoperative CT evaluation revealed no local recurrence or distant metastasis. The cat showed no abnormal findings at the time of writing (6 months postoperatively).

Relevance and novel information

Although osteosarcoma derived from the hyoid bone has rarely been reported in the veterinary field, this report suggests that such tumours may occur in cats. In addition, partial excision of the hyoid apparatus seems to be well tolerated in cats.

Comparison of surgical invasiveness between micro-endoscopic discectomy/microscopic discectomy and conventional hemilaminectomy in dogs

Micro-endoscopic discectomy (MED) or microscopic discectomy (MD) have been performed for disc herniation in humans. The purpose of this study was to compare the invasiveness of the hemilaminectomy in dogs between the approach using a cylindrical retractor for the MED/MD and a conventional open surgical approaches in dogs. First, as preliminary studies, we analyzed the suitability of the cylindrical retractor for the vertebral body of small to medium-sized dogs on the X-ray computed tomographic images using the three-dimensional analysis software, and confirmed that it was possible to open a bone window of　an approximate length of 1.72 clto the spinal canal with the cylindrical retractor with a diameter 17 mm using two medium-sized canine cadavers. Next, to determine difference in the invasiveness of hemilaminectomy, the magnitude of tissue damage, surgical stress and postoperative pain were compared between　the conventional open approach (hemilaminectomy group: HL group, n=6) and the surgical approach using the cylindrical retractor (MD group, n=6) in 12 beagle dogs. The plasma creatine phosphokinase, C-reactive protein and cortisol concentrations, incision length and University of Melbourne Pain Scale scores after the hemilaminectomy were significantly lower in the MD group than in the HL group. There were no significant differences between the durations of surgery and the other evaluated indices. The approach using the MD can provide a less invasive hemilaminectomy than the conventional approach in dogs.

Improving animal-specific radiotherapy quality assurance for kilovoltage X-ray radiotherapy using a 3D printed dog skull water phantom

Background

Accurate dose assessment during animal radiotherapy is beneficial for veterinary medicine and medical education.

Aim

To visualize the radiation treatment distribution of orthovoltage X-ray equipment in clinical practice using Monte Carlo simulations and create a dog skull water phantom for animal-specific radiotherapy.

Methods

EGSnrc-based BEAMnrc and DOSXYZnrc codes were used to simulate orthovoltage dose distributions. At 10, 20, 30, 40, 50, and 80 mm in a water phantom, the depth dose was measured with waterproof Farmer dosimetry chambers, and the diagonal off-axis ratio was measured with Gafchromic EBT3 film to simulate orthovoltage dose distributions. Energy differences between orthovoltage and linear accelerated radiotherapy were assessed with a heterogeneous bone and tissue virtual phantom. The animal-specific phantom for radiotherapy quality assurance (QA) was created from CT scans of a dog and printed with a three-dimensional printer using polyamide 12 nylon, with insertion points for dosimetry chambers and Gafchromic EBT3 film.

Results

Monte Carlo simulated and measured dose distributions differed by no more than 2.0% along the central axis up to a depth of 80 mm. The anode heel effect occurred in shallow areas. The orthovoltage radiotherapy percentage depth dose in bone was >40%. Build-up was >40%, with build-down after bone exit, whereas linear accelerator radiotherapy absorption changed little in the bone. A highly water-impermeable, animal-specific dog skull water phantom could be created to evaluate dose distribution.

Conclusion

Animal-specific water phantoms and Monte Carlo simulated pre-treatment radiotherapy are useful QA for orthovoltage radiotherapy and yield a visually familiar phantom that will be useful for veterinary medical education.

A Monte Carlo study on dose distribution of an orthovoltage radiation therapy system

It is important to plan radiotherapy treatment and establish optimal dose distribution to reduce the chances of side effects and injury. Because there are no commercially available tools for calculating dose distribution in orthovoltage radiotherapy in companion animals, we developed an algorithm to accomplish this and verified its characteristics using tumor disease cases. First, we used the Monte Carlo method to develop an algorithm to calculate the dose distribution of orthovoltage radiotherapy (280 kVp; MBR-320, Hitachi Medical Corporation, Tokyo, Japan) using BEAMnrc at our clinic. Using development of Monte Carlo method, dose distribution for tumor and normal organs were evaluated in brain tumors, squamous cell carcinomas of the head, and feline nasal lymphomas. In all cases of brain tumors, the mean dose delivered to the GTV ranged from 36.2 to 76.1% of the prescribed dose due to the decrease through the skull. In the nasal lymphoma in cats, the eyes with covered a 2 mm-thick lead plate, the respective average dose to the eyes was 71.8% and 89.9% less than that to the uncovered eyes. The findings may be useful for informed decision making in orthovoltage radiotherapy with more effective and targeted irradiation and data collection allowing detailed informed consent.

Histiocytic sarcoma with spinal necrosis in a dog with progressing non-ambulatory tetraparesis

Background: Histiocytic sarcoma (HS) is an aggressive malignant neoplasm, and widespread metastasis occurs with a fatal outcome. HS involving the central nervous system is relatively uncommon. Spinal cord necrosis, a very rare condition, could be induced by ischemia or infarction. Here, we report a dog progressing non-ambulatory tetraparesis with spinal cord necrosis caused by HS. Case Description: A 9-year-old male Labrador retriever was presented with a progressing non-ambulatory tetraparesis. CT imaging revealed lysis of the spinous process of T7 and a ring-shaped lesion surrounding the soft tissue of lung fields. T2-weighted MRI showed the spinous processes of T6 to T8 as hyperintense, and the lesion infiltrated into the T7 vertebra and the spinal cord. After euthanasia, the final diagnosis upon necropsy was HS, which was observed in the lung, spinous process, thoracic cord, and the pulmonary hilar lymph node. Moreover, necrotic spots were spread widely through the thoracic spinal cord. Conclusion: This report outlines a case of canine HS in the lung, spinous process, thoracic cord, and pulmonary hilar lymph node. Ischemic deficit and necrosis of the thoracic spinal cord resulted from the compression of perivascular tumor cells, which rapidly led to progressive tetraparesis. Although the diagnosis was difficult, MRI and CT images helped determine the prognosis. To our knowledge, this is the first case report of canine HS with direct spinal cord involvement associated with spinal necrosis.

Long-term survival of dogs with stage 4 oral malignant melanoma treated with anti-canine PD-1 therapeutic antibody: A follow-up case report

A monoclonal antibody targeting programmed cell death-1 (PD-1) is one of the most promising treatments for human cancers. Clinical studies in humans demonstrated that the anti-PD-1 antibody provides a long-lasting tumour response. Previously, we established an anti-canine PD-1 therapeutic antibody (ca-4F12-E6), and the pilot clinical study demonstrated that the antibody was effective in dogs with oral malignant melanoma (OMM). However, two OMM cases were still undergoing treatment when the pilot study was published. Here, we describe the long-term follow-up of those two cases. Although both cases showed long-term survival with complete response (CR), the tumour response differed; the effect onset was slow in one case and a durable response was observed in the second case even after treatment discontinuation. Secondary malignant tumours occurred during treatment in both cases. This follow-up study revealed that ca-4F12-E6 maintains CR in dogs for more than 1 year. In addition, the pattern of tumour response was unique compared to conventional therapy. These results indicate that new evaluation criteria for tumour response may be necessary for immunotherapy in veterinary medicine. Long-term follow-up is necessary regardless of the short-term treatment responsiveness.

Clinical relationship between histopathological necrotic/partial necrotic findings and disease condition of gallbladder mucoceles in dogs

Gallbladder mucocele (GM) is a common extrahepatic biliary disease recognized in dogs and is defined as the expansion and extension of the gallbladder by an accumulation of semi-solid bile or bile acid. Histopathological diagnosis of necrotizing cholecystitis and transmural coagulative necrosis of the gallbladder wall shows poor prognosis. Conversely, histopathological diagnosis with partial necrotic findings is often achieved. We hypothesized that histopathological partial necrosis of the gallbladder wall is the primary lesion of necrotic cholecystitis or transmural ischemic necrosis. Therefore, we investigated the relationship between histopathological necrosis/ partial necrosis findings and their clinical conditions. We retrospectively analyzed 55 dogs diagnosed with GM that had undergone cholecystectomy at the Yamaguchi University Animal Medical Center. The group with histopathological necrosis/partial necrosis of the gallbladder wall showed elevated levels of preoperative white blood cells, alanine transaminase, alkaline phosphatase, γ-glutamyltransferase, total bilirubin, and C-reactive protein compared to the non-necrotic group. Partial necrosis of the gallbladder wall may affect the progression of the disease and hematological abnormalities. Additionally, all death cases until 2 weeks were included in the histopathological necrosis/partial necrosis group. In this study, we found that poor prognosis factors were associated with partial necrosis of the gallbladder wall. Furthermore, these cases of partial necrosis showed elevated levels of blood test parameters. These results suggest that necrosis of the gallbladder wall is associated with poor prognosis and poor pathophysiological conditions.

Pedigree study of the heredity of copper-associated hepatitis in Dalmatians in Japan

The pedigrees of 3 Dalmatian dogs afflicted with copper-associated hepatitis were investigated to discover the mode of inheritance. A composite family pedigree showed that the 3 affected Dalmatians were related. None of the parents of the affected dogs showed clinical symptoms of liver disease, and the disease had no sex predisposition. The estimated segregation ratio was approximately 3:1 based on surviving littermates. These findings suggested that the copper-associated hepatitis in these Dalmatians was an autosomal recessive mode of inheritance. In addition, some male Dalmatians imported from abroad might have been involved in the occurrence of this disease in Japan.

Outcomes of megavoltage radiotherapy for canine intranasal tumors and its relationship to clinical stages

Background:

Radiation therapy is considered important for the treatment of intranasal tumors in dogs and is believed to be essential for prolonging their survival.

Aim:

To investigate the contribution of clinical staging to improve outcomes of megavoltage radiotherapy for canine intranasal tumors.

Methods:

A total of 123 dogs with intranasal tumors were included in the study. Forty-eight dogs received orthovoltage radiotherapy after cytoreductive surgery (Group I), 21 received orthovoltage radiotherapy without surgery (Group II), and 54 received megavoltage radiotherapy without surgery (Group III). All cases in each group were classified into clinical stages 1–4, and the median survival time (MST) was compared for each stage in all groups.

Results:

The overall MST was not significantly difference among Group I (325 days), Group II (317 days), and Group III (488 days); however, Group III was prolonged than Groups I and II. The MSTs for stages 1, 2, 3, and 4 were 597, 361, 267, and 325 days in Group I; 633, 260, 233, and 329 days in Group II; and 931, 860, 368, and 176 days in Group III, respectively. The MST for stage 2 cases in Group III was significantly prolonged when compared with that in Groups I and II; no significant difference was observed at other stages; however, the MST in Group III was longer in stage 1. These results showed that megavoltage radiotherapy prolonged the MST in dogs with intranasal tumors when compared to orthovoltage radiation with or without cytoreductive surgery, and that improvements in MST at stage 2 contributed significantly to this.

Conclusion:

The improvement in the MST in dogs with stages 1 and 2 intranasal tumors highlights the importance of starting megavoltage radiotherapy in the early stages.

Evaluation of setup errors of immobilization device for radiation therapy in companion animals

Background

Intensity-modulated radiotherapy (IMRT), which allows generating steep dose gradients, is a beneficial treatment for companion animals with adjacent target and risk organs. IMRT is essential for high setup accuracy for avoiding overdose to risk organs, and optimal radiotherapy is important for evaluating the setup accuracy of companion animals.

Aim

To use an immobilization device to evaluate setup errors in radiotherapy for companion animals.

Methods

We calculated setup errors in radiotherapy for 386 animals (dogs and cats; 3,261 registration images) that underwent radiotherapy between 2016 and 2022. The companion animals were immobilized with a customized bite block and vacuum lock device. A quantile-quantile plot with 95% confidence interval (CI) was used to evaluate the histogram of the setup errors, and the systematic and random setup errors were calculated for each region (brain, head and neck, chest and abdomen, pelvis, and spine).

Results

The setup error in each direction presented an extremely narrow-interval histogram, with the following lower and upper 95% CIs: cranial-caudal (-0.08, -0.06 cm); left-right (-0.04, -0.02 cm); and dorsal-ventral (-0.13, -0.11 cm). The mean systematic setup error was 0.16 cm (range: 0.12-0.36 cm), and the random error was 0.15 cm (range: 0.08-0.34 cm). The pelvis showed the highest systematic and random setup errors (mean: 0.36 and 0.23 cm, respectively).

Conclusion

The use of an immobilization device enables highly accurate radiotherapy for companion animals (95% CI < 0.15 cm).

A long survival case of spinal nephroblastoma in a dog

Background:

Dogs’ nephroblastoma of the spinal cord is a rare neoplastic disease, with few reports of long-term survival after surgery. We experienced that surgical treatment with postoperative radiation therapy for spinal nephroblastoma in a dog resulted in the long-term survival of 11 years.

Case Description:

The patient presented to our veterinary hospital because of progressive hindlimb paralysis. Based on diagnostic imaging, she was diagnosed with a thoracolumbar spinal cord tumor and was treated with surgery. The gross tumor tissue was removed after laminectomy, followed by postoperative radiation therapy using orthovoltage equipment. The histopathological features of the surgical specimen were consistent with those of previously reported spinal nephroblastoma, although infrequent mitotic figures were observed. The dog recovered well after treatment and resumed her normal walking condition. No tumor recurrence was observed on periodic follow-up magnetic resonance imaging performed 10 and 21 months after surgery. Imaging evaluation for the gradual development of hindlimb weakness was performed 9 years after surgery; however, no recurrence of tumor tissue was observed, and spondylosis deformans, probably induced after laminectomy, were identified as a possible cause. The dog died of aspiration pneumonia 11 years after surgery, independent of spinal nephroblastoma.

Conclusion:

To date, no clinical cases of canine spinal cord primary nephroblastoma that survived for 11 years after surgery have been reported. This case strongly suggests that providing intensive treatment for canine spinal nephroblastoma is very important.

Adjustment of multi-leaf collimator parameters in 4-MV and 6-MV IMRT: A study of veterinary clinical cases

Background:

For optimal treatment, it is important to maintain optimal multi-leaf collimator (MLC) transmission in intensity-modulated radiation therapy (IMRT). However, adjustment of transmissions has not been reported in veterinary medicine.

Aim:

To demonstrate that appropriate MLC parameter adjustment for IMRT using 4- and 6-MV energy can reduce the need for quality assurance revalidation in real companion animal clinical cases.

Methods:

The MLC parameters (leaf transmission and leaf offset) of the treatment planning system were adjusted by evaluating seven plans (10 × 10 cm, 3ABUT, DMLC, 7segA, FOURL, HDMLC, and HIMRT) and 20 preclinical cases (10 cases each in 4- and 6-MV groups). Subsequently, 101 IMRT plans of 88 cases (77 dogs and 11 cats) were evaluated for absolute dose of plan target volume (PTV) and organs at risk (OAR) and were analyzed for the relative dose distribution by gamma analysis (3%/3 mm, >10%) using EBT3 film.

Results:

After adjustment of the MLC parameters (leaf transmission and leaf offset, 4 MV: 0.008 and 0, 6 MV: 0.005 and 0, respectively), the data from 101 plans (4 MV: 64 plans and 6 MV: 37 plans) treated with IMRT showed PTV <3%, OAR <5%, and gamma analysis pass rates ≥95% in all cases.

Conclusion:

Clinically meaningful dose distributions can be created even with a limited validation device if the treatment parameters are adjusted appropriately, even for tumors in canines and felines, where the irradiation field is small, the target is adjacent to the OAR, and the target is often superficial.

Effect of drug-eluting bead transarterial chemoembolization loaded with cisplatin on normal dogs

Transcatheter arterial embolization (TAE) and transcatheter arterial chemoembolization (TACE) are standard treatments for advanced hepatocellular carcinoma (HCC) and particularly for unresectable tumors or liver metastases in humans. However, reports on TACE used in veterinary medicine are few. This study aimed to evaluate the feasibility and safety of drug-eluting bead transarterial chemoembolization (DEB-TACE). We performed DEB-TACE in four clinically normal dogs and pharmacokinetically compared the results against hepatic arterial infusion (HAI) of cisplatin in two dogs. Drug-eluting beads (DEB) loaded with cisplatin were injected through a microcatheter for selective embolization of the left hepatic artery. After embolization, computed tomography (CT) images and histological examination findings were obtained during a 4-week observation period. Serum platinum concentrations were measured to evaluate cisplatin after each procedure. Biochemical analysis was performed during a 12-week observation period. Embolization was successful in all dogs, and there were no clinically apparent abnormalities. Embolization was confirmed up to 4 weeks after DEB-TACE in two of the four dogs and up to 1 week in the other two dogs using postoperative CT images. Cisplatin was not detected in peripheral veins in all dogs after DEB-TACE, but it was detected in trace amounts after HAI. DEB-TACE using cisplatin was safe and well tolerated by normal dogs. DEB-TACE may be useful in terms of determining systemic toxicity and drug concentration within tumors.

Transient third-degree atrioventricular block during anesthesia in a cat

Background:

Third-degree atrioventricular block (AVB) is usually permanent, with transient cases being rare. Cats with transient third-degree AVB. It had been not reported in detail.

Case Description:

A 9.3-year-old, male shorthair cat was evaluated for possible nervous disease resulting from otitis interna. Under propofol and isoflurane anesthesia, this cat developed a third-degree AVB. Isoproterenol was administered by continuous infusion to increase its heart rate. During recovery, heart rate returned to sinus bradycardia together with first-degree AVB without medical treatment. The cause of transient AVB was not observed at the examination.

Conclusion:

The case of this cat suggests that anesthesia can result in a transient third-degree AVB.

Mismatch repair deficiency in canine neoplasms

The DNA mismatch repair (MMR) system preserves genomic stability by identifying and repairing mismatched nucleotides in the DNA replication process. The dysfunction of the MMR system, also known as mismatch repair deficiency (dMMR), is implicated as a predictive biomarker for the efficacy of immune checkpoint blockade therapy regardless of the tumor type in humans. This study aimed to evaluate the immunolabeling of MMR proteins in canine tumors and to identify the types of tumors having dMMR. First, we performed immunohistochemistry in 8 different canine tumors (oral malignant melanoma, high-to-intermediate grade lymphoma, mast cell tumor, malignant mammary gland tumor, urothelial carcinoma, hepatocellular carcinoma, osteosarcoma, and hemangiosarcoma) with 15 samples each to analyze the immunolabeling of canine mismatch repair proteins (MSH2, MSH6, and MLH1) using anti-human monoclonal antibodies. We found that more than half of canine oral malignant melanoma (60%) and hepatocellular carcinoma (53%) samples and fewer of the other canine tumors had loss of immunolabeling in ≥1 MMR protein (ie, evidence of defective MMR proteins, based on the definition of dMMR in the humans). Antibodies against human MSH2, MSH6, and MLH1 were cross-reactive with the corresponding canine protein as confirmed using MMR gene knockout canine cell lines. Further studies are required to investigate the clinical outcomes in canine spontaneous tumors with dMMR to determine the potential for immune checkpoint blockade therapy for these tumor types.

Sphere-forming cells display stem cell-like characteristics and increased xCT expression in a canine hepatocellular carcinoma cell line

Hepatocellular carcinoma (HCC) is the most common type of canine primary liver tumor; however, most chemotherapies against HCC are ineffective due to resistance to anticancer agents. Sphere-forming cells are considered to act as cancer stem cells for various types of solid tumors and have been established for many canine tumor cell lines, yet no studies have reported sphere-forming cells for canine HCC. In this study, we established sphere-forming cells from a canine HCC cell line (AZACH). These cells displayed increased stem cell marker mRNA expression (Nanog, Sox2, c-Myc, and Klf4), aldehyde dehydrogenase activity, and chemoresistance against mitoxantrone, gemcitabine, and doxorubicin. In addition, sphere-forming cells exhibited higher xCT expression and lower intracellular reactive oxygen species levels than adherent cells. Treatment with sulfasalazine, a xCT-specific inhibitor, reduced sphere formation efficiency. Together, these results indicate that sphere-forming cells derived from a canine HCC cell line have similar characteristics to cancer stem cells and that their increased xCT expression and associated resistance to oxidative stress contribute toward sphere formation.

Copper-associated hepatitis in a young Dalmatian dog in Japan

A male 25-month-old Dalmatian dog attended our veterinary hospital because of anorexia and high circulating liver enzyme activities. Abdominal computed tomography showed a slightly small liver with rounded edges, and laparoscopic examination showed that the liver was yellowish. Histopathological examination revealed multifocal necrosis of hepatocytes and severe chronic hepatitis. Rhodanine staining showed severe copper accumulation in hepatocytes and a quantitative analysis of the copper content of the liver showed substantial accumulation (10.3 mg/g dry mass), suggesting a diagnosis of copper-associated hepatitis. Previously reported canine mutation in the COMMD1, the gene responsible for the copper-associated hepatitis in the Bedlington terrier, was not identified. To our knowledge, this is the first report of copper-associated hepatitis in a Dalmatian in Japan.

Clinical features and their course of pituitary carcinoma with distant metastasis in a dog

An 11-year-old male toy poodle with neurological symptoms was diagnosed with a macroscopic pituitary tumor, which produced adrenocorticotropic hormone. Radiation therapy with a linear accelerator was performed for the pituitary tumor, and resulted in good local tumor control. However, serum endogenous adrenocorticotropic hormone concentrations were uncontrollable even after the tumor disappeared. Abdominal computed tomography revealed splenic masses, and splenectomy was performed. Histopathological examination of the surgical specimen showed tumor cells with eosinophilic and finely granular cytoplasm suggestive of endocrine origin. Since these cells were positive for adrenocorticotropic hormone, the case was diagnosed as a pituitary carcinoma with distant metastasis. Necropsy revealed multiple metastases to the abdominal organs. This is the first case report describing canine pituitary carcinoma with distant metastasis.

Cystine transporter expression is a marker to identify a subpopulation of canine adipose-derived stem cells

Adipose-derived stem cells (ADSCs) are promising cell sources for regenerative medicine due to the simplicity of their harvest and culture; however, their biological properties are not completely understood. Moreover, recent murine and human studies identified several functional subpopulations of ADSCs varying in differentiation potential; however, there is a lack of research on canine ADSCs. Cystine transporter (xCT) is a stem cell marker in gastric and colon cancers that interacts with CD44 to enhance cystine uptake from the cell surface and subsequently accelerates intercellular glutathione levels. In this study, we identified a ~5% functional subpopulation of canine ADSCs with xCT⁺ expression (xCT^Hi). Compared with those of the xCT⁻ subpopulation (xCT^Lo), the xCT^Hi subpopulation showed a significantly higher proliferation rate, higher expression of conventional stem cell markers (SOX2, KLF4, and c-Myc), and higher expression of adipogenic markers (FABP4 and PPARγ). By contrast, the xCT^Lo subpopulation showed significantly higher expression of osteogenic markers (BMP1 and SPP) than xCT^Hi cells. These results suggest xCT as a candidate marker for detecting a functional subpopulation of canine ADSCs. Mechanistically, xCT could increase the adipogenic potential while decreasing the osteogenic differentiation potential, which could serve as a valuable target marker in regenerative veterinary medicine.

Oncolytic reovirus therapy: Pilot study in dogs with spontaneously occurring tumours

Oncolytic virotherapy is a novel treatment involving replication-competent virus in the elimination of cancer. We have previously reported the oncolytic effects of reovirus in various canine cancer cell lines. This study aims to establish the safety profile of reovirus in dogs with spontaneously occurring tumours and to determine a recommended dosing regimen. Nineteen dogs with various tumours, mostly of advanced stages, were treated with reovirus, ranging from 1.0 × 10⁸ to 5.0 × 10⁹ TCID₅₀ given as intratumour injection (IT) or intravenous infusion (IV) daily for up to 5 consecutive days in 1 or multiple treatment cycles. Adverse events (AEs) were graded according to the Veterinary Cooperative Oncology Group- Common Terminology Criteria for Adverse Events (VCOG-CTCAE) v1.1 guidelines. Viral shedding, neutralizing anti-reovirus antibody (NARA) production and immunohistochemical (IHC) detection of reovirus protein in the tumours were also assessed. AE was not observed in most dogs and events were limited to Grade I or II fever, vomiting, diarrhoea and inflammation of the injected tumour. No infectious virus was shed and all dogs had elevated NARA levels post-treatment. Although IHC results were only available in 6 dogs, 4 were detected positive for reovirus protein. In conclusion, reovirus is well-tolerated and can be given safely to tumour-bearing dogs according to the dosing regimen used in this study without significant concerns of viral shedding. Reovirus is also potentially effective in various types of canine tumours.

Aldehyde dehydrogenase activity helps identify a subpopulation of murine adipose-derived stem cells with enhanced adipogenic and osteogenic differentiation potential

AIM

To identify and characterize functionally distinct subpopulation of adipose-derived stem cells (ADSCs).

METHODS

ADSCs cultured from mouse subcutaneous adipose tissue were sorted fluorescence-activated cell sorter based on aldehyde dehydrogenase (ALDH) activity, a widely used stem cell marker. Differentiation potentials were analyzed by utilizing immunocytofluorescece and its quantitative analysis.

RESULTS

Approximately 15% of bulk ADSCs showed high ALDH activity in flow cytometric analysis. Although significant difference was not seen in proliferation capacity, the adipogenic and osteogenic differentiation capacity was higher in ALDH^Hi subpopulations than in ALDH^Lo. Gene set enrichment analysis revealed that ribosome-related gene sets were enriched in the ALDH^Hi subpopulation.

CONCLUSION

High ALDH activity is a useful marker for identifying functionally different subpopulations in murine ADSCs. Additionally, we suggested the importance of ribosome for differentiation of ADSCs by gene set enrichment analysis.

Comparison of postoperative pain and inflammation reaction in dogs undergoing preventive laparoscopic-assisted and incisional gastropexy

This study compared the effects of postoperative pain and inflammation reaction after preventive laparoscopic-assisted gastropexy (LAG) and incisional gastropexy (IG) in 10 clinically normal Beagles. Surgical time, incision length, visual analog scale (VAS) score, University of Melbourne Pain Scale (UMPS) score, and plasma C-reactive protein (CRP), plasma cortisol (COR), and serum interleukin-6 (IL-6) levels were evaluated. The VAS and UMPS scores and COR and IL-6 levels were recorded at 0.5, 1, 2, 4, 8, 12, 18 and 24 hr after surgery. CRP level was recorded at 12, 24 and 48 hr after surgery. The VAS and UMPS scores showed no significant intergroup differences. Compared to IG, LAG had significantly lower surgical time (45 ± 9.91 min vs 64 ± 5.30 min; P<0.05), incision length (46 ± 8.21 mm vs 129 ± 19.49 mm; P<0.05), CRP level (12 hr after surgery; 4.58 ± 1.58 mg/dl vs 12.4 ± 1.34 mg/dl; P<0.01), and COR level (1 hr after surgery; 10.79 ± 3.07 µg/dl vs 15.9 ± 3.77 µg/dl; P<0.05). IL-6 levels showed no significant intergroup differences at any time point. However, LAG resulted in lower IL-6 levels than did IG at all postoperative time points. Neither procedure resulted in significant surgical complications. LAG produced lower surgical stress than did IG, suggesting that LAG is a safe, minimally invasive, and highly useful technique for preventing canine gastric dilatation-volvulus. Nevertheless, since this study used experimental models, its usefulness should be evaluated in future cases.

Identification of rhodamine 123-positive stem cell subpopulations in canine hepatocellular carcinoma cells

The majority of cases of chemotherapy for hepatocellular carcinoma (HCC) are not effective in human or veterinary medicine due to resistance against anticancer agents. In human medicine, hepatocellular carcinoma stem cells (HCSCs) were recently identified as cytokeratin 19 (CK19)-, cluster of differentiation (CD)-44-, and CD133-positive. However, there are few previous reports regarding canine HCSC (cHCSC). Additionally, to the best of our knowledge, the chemoresistance against anticancer agents of these cHCSCs has not been investigated. In the present study staining of cHCSCs was performed with rhodamine 123, a low-toxicity fluorescent dye for mitochondria, by flow cytometry. There were two subpopulations in the HCC cell line defined by their higher (Rho^Hi) and lower (Rho^Lo) fluorescence intensity of rhodamine 123. The Rho^Hi subpopulation demonstrated a higher Nanog gene expression, sphere-forming ability, and chemoresistance against gemcitabine. However, there was no significant difference between Rho^Hi and Rho^Lo regarding the proliferation rate and chemoresistance against mitoxantrone and doxorubicin. The present results indicate that the expression of rhodamine 123 identifies different stem cell subpopulations in a canine HCC cell line.

Effects of toceranib phosphate (Palladia) monotherapy on multidrug resistant lymphoma in dogs

We examined whether multidrug resistant (MDR) canine lymphoma increases gene expression for platelet-derived growth factor receptor α (PDGFRα), vascular endothelial growth factor receptor 2 (VEGFR2), and c-KIT, and whether toceranib phosphate (TOC) has potential as a treatment for MDR canine lymphoma. The clinical data showed that PDGFRα expression was higher in canine subjects with MDR T-cell lymphoma than in those with untreated T-cell lymphoma, and that c-KIT expression was greater in subjects with T-cell lymphoma than in those with B-cell lymphoma. TOC monotherapy was well tolerated without serious adverse effects, and two of the five subjects that received TOC exhibited partial responses. The data presented here could contribute to the assessment of TOC-based therapy for dogs with MDR or T-cell lymphoma.

Aldehyde dehydrogenase activity identifies a subpopulation of canine adipose-derived stem cells with higher differentiation potential

Adipose-derived stem cells (ADSCs) are abundant and readily obtained, and have been studied for their clinical applicability in regenerative medicine. Some surface antigens have been identified as markers of different ADSC subpopulations in mice and humans. However, it is unclear whether functionally distinct subpopulations exist in dogs. To address this issue, we evaluated aldehyde dehydrogenase (ALDH) activity—a widely used stem cell marker in mice and humans—by flow cytometry. Approximately 20% of bulk ADSCs showed high ALDH activity. Compared to cells with low activity (ALDH^Lo), the high-activity (ALDH^Hi) subpopulation exhibited a higher capacity for adipogenic and osteogenic differentiation. This is the first report of distinct ADSC subpopulations in dogs that differ in terms of adipogenic and osteogenic differentiation potential.

Craniocervical junction abnormalities with atlantoaxial subluxation caused by ventral subluxation of C2 in a dog

Craniocervical junction abnormalities with atlantoaxial subluxation caused by ventral subluxation of C2 were diagnosed in a 6-month-old female Pomeranian with tetraplegia as a clinical sign. Lateral survey radiography of the neck with flexion revealed atlantoaxial subluxation with ventral subluxation of C2. Computed tomography revealed absence of dens and atlanto-occipital overlapping. Magnetic resonance imaging showed compression of the spinal cord and indentation of caudal cerebellum. The diagnosis was Chiari-like malformation, atlantoaxial subluxation with ventral displacement of C2, atlanto-occipital overlapping, and syringomyelia. The dog underwent foramen magnum decompression, dorsal laminectomy of C1, and ventral fixation of the atlantoaxial joint. Soon after the operation, voluntary movements of the legs were recovered. Finally, the dog could stand and walk without assistance. The dog had complicated malformations at the craniocervical junction but foramen magnum decompression and dorsal laminectomy for Chiari-like malformation, and ventral fixation for atlantoaxial subluxation resulted in an excellent clinical outcome.

Hypoxia-activated prodrug TH-302 decreased survival rate of canine lymphoma cells under hypoxic condition

We tested the hypotheses that hypoxic stimulation enhances growth potentials of canine lymphoma cells by activating hypoxia-inducible factor 1α (HIF-1α), and that the hypoxia-activated prodrug (TH-302) inhibits growth potentials in the cells. We investigated how hypoxic culture affects the growth rate, chemoresistance, and invasiveness of canine lymphoma cells and doxorubicin (DOX)-resistant lymphoma cells, and influences of TH-302 on survival rate of the cells under hypoxic conditions. Our results demonstrated that hypoxic culture upregulated the expression of HIF-1α and its target genes, including ATP-binding cassette transporter B1 (ABCB1), ATP-binding cassette transporter G2 (ABCG2), platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF), and survivin, and enhanced the growth rate, DOX resistance, and invasiveness of the cells. Additionally, TH-302 decreased the survival rate of the cells under hypoxic condition. Our studies suggest that hypoxic stimulation may advance the tumorigenicity of canine lymphoma cells, favoring malignant transformation. Therefore, the data presented may contribute to the development of TH-302-based hypoxia-targeting therapies for canine lymphoma.

Clinical outcomes of suspected ischemic myelopathy in cats

Ischemic myelopathy is a disorder of acute onset that is characterized by nonprogressive paresis/plegia. Magnetic resonance imaging (MRI) is particularly helpful in supporting the antemortem diagnosis of ischemic myelopathy. Cats, which were suspected to have ischemic myelopathy between 2005 and 2008, were reviewed retrospectively. The acute onset of nonprogressive and nonpainful myelopathy, the conduct of spine MRI, and the availability of complete medical records were included in the inclusion criteria. The presumptive diagnosis was based on medical history as well as clinical, cerebrospinal fluid, and MRI findings. Six cats met the inclusion criteria based on medical records that had been made for about 3 years, and had relatively good prognoses. The less number of patients with ischemic myelopathy has been reported in cats than in dogs. However, the number of cats with ischemic myelopathy in clinical settings appears to be greater than previously considered.

GM2 gangliosidosis variant 0 (Sandhoff-like disease) in a family of toy poodles

BACKGROUND

GM2 gangliosidosis variant 0 (human Sandhoff disease) is a lysosomal storage disorder caused by deficiencies of acid β-hexosaminidase (Hex) A and Hex B because of an abnormality of the β-subunit, a common component in these enzyme molecules, which is coded by the HEXB gene.

OBJECTIVE

To describe the clinical, pathological, biochemical, and magnetic resonance imaging (MRI) findings of Sandhoff-like disease identified in a family of Toy Poodles.

ANIMALS

Three red-haired Toy Poodles demonstrated clinical signs including motor disorders and tremor starting between 9 and 12 months of age. The animals finally died of neurological deterioration between 18 and 23 months of age. There were some lymphocytes with abnormal cytoplasmic vacuoles detected.

METHODS

Observational case study.

RESULTS

The common MRI finding was diffuse T2-hyperintensity of the subcortical white matter in the cerebrum. Bilateral T2-hyperintensity and T1-hypointensity in the nucleus caudatus, and atrophic findings of the cerebrum and cerebellum, were observed in a dog in the late stage. Histopathologically, swollen neurons with pale to eosinophilic granular materials in the cytoplasm were observed throughout the central nervous system. Biochemically, GM2 ganglioside had accumulated in the brain, and Hex A and Hex B were deficient in the brain and liver. Pedigree analysis demonstrated that the 3 affected dogs were from the same family line.

CONCLUSIONS AND CLINICAL IMPORTANCE

The Sandhoff-like disease observed in this family of Toy Poodles is the 2nd occurrence of the canine form of this disease and the 1st report of its identification in a family of dogs.

Fibrocartilaginous embolism of the spinal cord diagnosed by characteristic clinical findings and magnetic resonance imaging in 26 dogs

Fibrocartilaginous embolism (FCE) is a disorder of acute onset that presents with nonprogressive ataxia. We performed a retrospective examination of FCE of the spinal cord diagnosed by characteristic clinical findings and magnetic resonance imaging (MRI) in 26 dogs. In the present study, treatment consisting of physiotherapy alone, or this in combination with corticosteroid administration, was initiated immediately following diagnosis of FCE. Age at onset and the gender ratio in the present study closely correlated with those previously reported. In the present study, 88% of the dogs that developed FCE were small- to medium-sized, which is different from previously reported studies. There is a possibility that FCE also develops relatively frequently in small- to medium-sized dogs. No significant difference was observed between the physiotherapy alone and the physiotherapy and corticosteroids groups of dogs. FCE development has been reported predominantly at the vertebral levels C6-T2 and L4-S3 and less frequently at C1-5 and T3-L3. However, in the present study, FCE developed predominantly at T3-L3. FCE developed at T3-L3 or C1-5 in 69% of the cases in the present study, suggesting that there is relatively frequent development of FCE at these vertebral levels. The recovery time of T3-L3 was the shortest (10.2 +/- 7.4 days), and that of C1-5 was next-shortest (15.8 +/- 5.4) in this study. This suggested the possibility that the detection ratio of cases was low, because the symptoms in cases of FCE that has developed in C1-5 and T3-L3 would have improved before inspection in the secondary institution, where the MRI and diagnosis were performed.

Malignant mixed tumor in the salivary gland of a cat

The presence of a malignant mixed tumor, also known as a carcinosarcoma, in the salivary gland is very rare. Such tumors, which are typically aggressive, are characterized by the presence of carcinomatous and sarcomatous components. A 9-year-old neutered female domestic short-haired cat presented with swelling in the right mandibular lesion that had rapidly enlarged over the previous 3 weeks. Physical examination revealed a large, fluctuated and painless subcutaneous swelling that was associated with a firm mass. Radiographs of the head revealed a soft-tissue density that involved faint circular calcific opacity. Contrast-enhanced computed tomography revealed that the peripheral capsulated cystic area had a contrast enhanced region without bone lysis. The cat received a total excision of the mass and postoperative radiotherapy. Histopathological analysis of the mass revealed that it was a malignant mixed tumor. Metastasis to the lung was discovered 7 weeks later, at which time treatment was stopped.

Usefulness of an early diagnosis for the favorable prognosis of fibrocartilaginous embolism diagnosed by magnetic resonance imaging in 10 small- to middle-sized dogs

Fibrocartilaginous embolism (FCE), a disorder of rapid onset featured by nonprogressive paralysis and paresis of four legs, shows clinical symptoms very similar to those of other disorders, e.g., disk herniation. We examined 10 animals diagnosed with FCE based on clinical symptoms and magnetic resonance imaging (MRI) findings in a retrospective study to examine the relationship between onset-to-diagnosis/treatment initiation time and prognosis of FCE. Statistical procedures, including Fisher's exact probability test, were conducted. All animals in a group, in which the diagnosis was made and treatment was initiated after an elapse of <15 days after onset, showed improved symptoms; the group showed a positive correlation (r = 0.76) between "onset-to-symptom improvement time" and "onset-to-diagnosis/treatment initiation time". Furthermore, the mean onset-to-diagnosis/ treatment initiation times were 2.67 days and 10.25 days in groups without and with sequelae, respectively; the time was significantly (P < 0.02) shorter in the group without sequelae. A significant difference was found between the groups in early diagnosis and treatment initiation. Our study indicates that the early precise diagnosis for acutely developed paralysis and paresis of four legs through testings including MRI, as well as the early onset of their treatment are important to obtain a favorable prognosis.

Primary chondrosarcoma in the skull of a dog

Chondrosarcoma of the skull is a rare primary malignant tumor that is slow-growing, but locally aggressive. A 5-year-old, golden retriever was presented to our hospital with a swelling in the left side of her head, and the swelling had slowly enlarged over the previous month. There were no significant changes on the neurological examination. A computed tomography scan revealed a large mass involving bone destruction and prominent matrix mineralization. T1-weighted magnetic resonance imaging showed a slightly low-signal intensity area and a T2-weighted image revealed marked, high-signal intensity. There was compression of the adjacent brain parenchyma. Histopathological examination confirmed the lesion to be a chondrosarcoma.

Expression of the MDR1 gene and P-glycoprotein in canine mast cell tumor cell lines

Cellular drug resistance to antineoplastic drugs is often due to the presence of a drug efflux pump that reduces intracellular drug accumulation and chemosensitivity. P-glycoprotein (P-gp), which is encoded by the MDR1 gene, is considered to function as an ATP-driven membrane drug efflux pump and appears to play an important role in tumor cell resistance. In the present report, we assessed the expression of MDR1 by RT-PCR in three canine mast cell tumor cell lines, TiMC, CoMS and LuMC, originating from a cutaneous tumor, an oral-mucosal tumor and a gastrointestinal tumor, respectively. P-gp expression was also examined by Western blot analysis, while the functional activity of P-gp was assessed by flowcytometric analysis of intracellular rhodamine-123 (Rhd-123) uptake. The results revealed that MDR1 gene and P-gp were both expressed in CoMS and LuMC cells, whereas neither was present in TiMC cells. In CoMS and LuMC cells, intracellular uptake of Rhd-123 increased in the presence of verapamil, a functional modulator of P-gp. In contrast, TiMC cells did not show any changes in the intracellular accumulation of Rhd-123 after the verapamil addition. These findings suggest that the expressions of MDR1 gene and P-gp probably contribute to cellular drug resistance in canine mast cell tumors.

Maxillofacial rhabdomyosarcoma in the canine maxillofacial area

Three dogs had a diagnosis of maxillofacial rhabdomyosarcoma. These dogs were treated with surgery and/or radiotherapy, and had poor clinical responses. The tumor tissues in all three cases were observed around the upper premolar teeth with ulcerative lesions and CT examinations in each case revealed extensive bony involvement into the maxilla. Two cases were subjected to surgical excision of the tissues, followed by an external radiation therapy. The other case was only treated with palliative radiation. Outcomes of the treatment of all the cases were quite poor because of the invasive and refractory nature of the tumor cells, leading to the local recurrence and lung metastasis early in the clinical course. All dogs died within two months of the first admission.

Activity of matrix metalloproteinase-2 (MMP-2) in canine oronasal tumors

Activity of matrix metalloprotease-2 (MMP-2) and the expression of its related molecules were examined in spontaneous canine oronasal tumors. Tissue samples from melanoma and squamous cell carcinoma possessed higher MMP-2 activity, as shown in gelatin zymography, in comparison with acanthomatous epulis and nasal adenocarcinoma. Regional lymph node invasion and distant metastases were more frequently observed in the MMP-2 positive cases. There were no significant differences by RT-PCR examination in the expression of the genes encoding MMP-2, MT1-MMP and TIMP-2 among the tumor histological types. However, the MMP-2/TIMP-2 ratio showed a significantly higher level of the genes in the malignant oral melanoma and squamous cell carcinoma. The MMP-2/TIMP-2 ratio was also positively correlated with MMP-2 activity in gelatin zymography. These results indicate that the MMP-2/TIMP-2 ratio may be of value in evaluating the prognosis in canine oronasal cavity tumors.

Application of ventriculoperitoneal shunt as a treatment for hydrocephalus in a dog with syringomyelia and Chiari I malformation

A twenty-month-old Chihuahua male dog was presented to us suffering with ataxia. Based on the physical examination, X-ray and magnetic resonance imaging (MRI) examinations, we diagnosed the dog with hydrocephalus, Chiari I malformation and syringomyelia. Treatment consisted of internal medical treatment and the placement of a ventriculoperitoneal (VP) shunt. The ventricular dilatation was relieved and the dog improved neurologically; however, the Chiari I malformation and syringomyelia remained after surgically positioning the VP shunt.

Cloning of the feline GADD45 cDNA and analysis of its mutation in feline lymphoma cell lines

Growth arrest and DNA damage-inducible protein 45 (GADD45) plays an important role in suppressing multistep carcinogenesis. In this report, we describe the isolation of the complete wild-type feline GADD45 cDNA from feline tissues. Expression of feline GADD45 mRNA was detected in the liver, spleen, kidney, lung, and testis. The predicted amino acid sequences encoded by the full-length feline GADD45 cDNA display sequence homology with those from other vertebrates, and as in the case of human GADD45, cell growth suppression was observed by ectopic expression of feline GADD45. However, no mutations were detected by sequence analysis of feline GADD45 in several feline lymphoma cell lines, indicating that the GADD45 mutation might be uncommon in feline oncogenesis.

Nucleotide sequence of complementary DNA encoding for quaking protein of cow, horse and pig

Complementary DNA (cDNA) for bovine quaking gene (Bqk), equine quaking gene (Eqk) and porcine quaking gene (Pqk), which are homologous to mouse quaking gene (qkI), were isolated, and their nucleotide sequences were determined. cDNA sequences of Bqk, Eqk and Pqk showed very high homology to that of qkI at nucleotide level; 94.2, 95.7 and 95.6%, respectively. Deduced amino acid sequences for Bqk, Eqk and Pqk perfectly matched to that of qkI. These findings suggest that the quaking gene family is highly conserved during mammalian evolution, and that Bqk, Eqk and Pqk are likely to have important biological functions also in cow, horse and pig.

Spontaneous Feline Mammary Carcinoma Is a Model of HER2 Overexpressing Poor Prognosis Human Breast Cancer

Companion animal spontaneous tumors are suitable models for human cancer, primarily because both animal population and the tumors are genetically heterogeneous. Feline mammary carcinoma (FMC) is a highly aggressive, mainly hormone receptor–negative cancer, which has been proposed as a model for poor prognosis human breast cancer. We have identified and studied the feline orthologue of the HER2 gene, which is both an important prognostic marker and therapeutic target in human cancer. Feline HER2 (f-HER2) gene kinase domain is 92% similar to the human HER2 kinase. F-HER2–specific mRNA was found 3- to 18-fold increased in 3 of 3 FMC cell lines, in 1 of 4 mammary adenomas and 6 of 11 FMC samples using quantitative reverse transcription-PCR. Western blot showed that an anti-human HER2 antibody recognized a protein comigrating with the human p185HER2 in FMC cell lines. The same antibodies strongly stained 13 of 36 FMC archival samples. These data show that feline HER2 overexpression qualifies FMC as homologous to the subset of HER2 overexpressing, poor prognosis human breast carcinomas and as a suitable model to test innovative approaches to therapy of aggressive tumors.

Spontaneous feline mammary carcinoma is a model of HER2 overexpressing poor prognosis human breast cancer

Companion animal spontaneous tumors are suitable models for human cancer, primarily because both animal population and the tumors are genetically heterogeneous. Feline mammary carcinoma (FMC) is a highly aggressive, mainly hormone receptor-negative cancer, which has been proposed as a model for poor prognosis human breast cancer. We have identified and studied the feline orthologue of the HER2 gene, which is both an important prognostic marker and therapeutic target in human cancer. Feline HER2 (f-HER2) gene kinase domain is 92% similar to the human HER2 kinase. F-HER2-specific mRNA was found 3- to 18-fold increased in 3 of 3 FMC cell lines, in 1 of 4 mammary adenomas and 6 of 11 FMC samples using quantitative reverse transcription-PCR. Western blot showed that an anti-human HER2 antibody recognized a protein comigrating with the human p185HER2 in FMC cell lines. The same antibodies strongly stained 13 of 36 FMC archival samples. These data show that feline HER2 overexpression qualifies FMC as homologous to the subset of HER2 overexpressing, poor prognosis human breast carcinomas and as a suitable model to test innovative approaches to therapy of aggressive tumors.